In some catheterization therapies, a first catheter is preferably removed from the body after therapy and replaced with a second catheter.
One example of this exchange is in the use of balloon catheters in the treatment of stenosis in arteries. A current technique is the expansion of a partially occluded lumen in an artery through the use of a first balloon of a low profile. Once a lesion is opened, a larger balloon may be used to complete the opening of the occluded area.
The exchange of catheters can be a complex task. Prior art catheters commonly were inserted over a guidewire which extended in a lumen through the catheter. It was difficult to feed such a catheter onto a guidewire while a guidewire was in the body because of friction encountered when feeding the catheter through the artery. Additionally, the guidewire must be held while a catheter is loaded over it. Previously a physician loaded the catheter over a guidewire extension outside of the body and then slid it over the portion of the guidewire inside the body. This required a long guidewire extension outside the body as the guidewire extension had to be longer than the catheter. This long guidewire extension was difficult to keep out of the way during the surgical process. It also required an additional individual to handle the guidewire during the exchange process.
Various techniques have been tried to overcome this. For example, the catheter disclosed in U.S. Pat. No. 4,762,129 to Bonzel has a short lumen through the interior of a balloon. In Bonzel, the balloon lumen rides on the guidewire and the guidewire is outside the rest of the catheter body. In this way, only a portion of the guidewire which is as long as the balloon need extend outside the body for loading. The catheter itself must be stiff enough to be independently pushed through the artery.
Rapid exchange catheter art includes internal dual lumen apparatus and related devices such as U.S. Pat. Nos. 5,061,273 and 5,040,548 to Yock. Other rapid exchange techniques include slitted exchange sleeves such as that shown in U.S. Pat. No. 4,748,982 to Horzewski or U.S. Pat. No. 4,824,435 to Giesy as well as guiding tip rings such as U.S. Pat. No. 4,824,435 to Giesy. The narrow loop width of such guiding tip rings offer little support and reduce the pushability and tracking of their attached devices.
This description of art is not intended to constitute an admission that any patent, publication or other information referred to is "prior art" with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. .sctn. 1.56(a) exists.
What is needed is a catheter design with a low profile through the balloon area, preferably with support for a guidewire in more locations along the catheter, to aid in pushability as well as aiding the tracking of the attached device. Additionally, a catheter with a smaller shaft size is desirable. Current fixed wire catheters, sometimes known as balloons on wires, are unable to maintain position within a select vessel as easily as over-the-wire catheters. A catheter is needed which allows a wire to be left behind following therapy. The wire is then advanced with the catheter across the diseased area. The wire is deployed distal to the diseased area and the catheter is removed.